Hubble's images have graced the front pages of our newspapers, inspired thousands to look at the sky and think about our place in the universe. They've even been made into high-fashion dresses worn by the wife of Britain's prime minister, Samantha Cameron. If you've seen any pictures of stars, nebulae or galaxies in the past 20 years, there's a good chance they were taken by Hubble.

Don't let the pretty pictures fool you: Hubble is a formidable scientific observatory, and its data has revolutionised our understanding of the universe. Competition to use its instruments is fierce as ever. But at 20 years old, Hubble is nearing retirement. JWST's main mirror has more than six times the area of Hubble's, and the telescope is designed specifically to push ahead in those areas where Hubble made its biggest breakthrough contributions. The performance we can expect from JWST is so much better than any similar instrument or telescope on the horizon. Its impact is almost certain to rival that of Hubble.

Last Thursday, the subcommittee in the US House Appropriations Committee responsible for the science, commerce and justice budget passed a bill with little fanfare that would withdraw all funding for the mission, following criticism of top-level management and budget overruns. It's just the first step in what is likely to be a drawn-out drama, in which the bill will be bounced around between various committees in House and Senate for months to come. A tough battle for the JWST's survival lies ahead.

What would cancellation mean for science, and for society? To me, the Hubble experience is key. What would we have missed in the past 20 years without Hubble?

Hubble's observations have proven crucial in many of the most significant scientific breakthroughs in recent history, with important contributions stretching across all areas of astronomy. Its early observations in the 1990s of galaxies in the distant universe have launched one of the most active fields in astrophysics research today, the study of galaxy evolution throughout cosmic history. For the first time galaxies other than our close neighbours could be imaged in such detail that we could see their shapes, sizes, even watch their stars blink and explode, and measure their distances. With Hubble's newest instruments, we've been able to look back more than 13bn years in time, when the universe was just a couple of hundred million years old. That is simply incredible.

Hubble's exquisite image quality also provided the first visual confirmation of the existence of planets around other stars in the Milky Way. This provided a huge impetus to the rapidly expanding field of exoplanet studies and the search for life elsewhere in the universe. Importantly, Hubble's entire data archive is open to everyone, and Nasa hosts a huge archive of its images that are free to download and use. As a result, Hubble has found its way into popular culture, fashion, art and education, more than any other scientific instrument before. The observatory has inspired a generation of children, including myself and many of my peers, to take an interest in science and technology. That, to me, is as important as the scientific results Hubble has produced.

Needless to say, seeing JWST among the "extraneous, duplicative and unnecessary programmes" that the House has proposed to cut comes as a shock.

The crucial point to the proposed budget is that the money taken from the JWST mission is removed from the Nasa budget entirely. It will not go into other missions or research grants. Some $3bn has already been spent in the US alone, simply to be written off. Around 2,000 US jobs are thought to be on the line. The European Space Agency is a 15% partner in JWST, its Canadian counterpart will contribute over $100m. The stakes here in Europe are high too.

Hubble cost several billion dollars more than initially planned, and its launch was delayed by almost a decade. Yet now, 20 years on, no one debates whether those funds were well spent. Will its successor leave the same legacy? And, more importantly, can we afford not to find out?

It's hard to see who will be better off if JWST really is axed. For scientists, its loss will slow progress in understanding the physics that governs the universe at a time when huge advances are within our reach. Engineers, who have successfully completed many aspects of the observatory, will see more than a decade of work go to waste.

The public will lose the opportunity to marvel once again at the amazing place that is our universe: the thousands of planets that populate our own galaxy, the places where new suns are born, the first galaxies at the dawn of time. We'll all miss out on the opportunity to inspire a new generation of scientists by simply being capable, as a species, of launching this fantastic telescope into space and seeing the things it will see.

Frankly, I think cost-saving exercises don't come much more short-sighted than this. Whatever the problems with the mission, I think it's our duty to find a solution that will see JWST launched. I hope the US government will come to the same conclusion.

Sarah Kendrew is an engineer at the Max Planck Institute for Astronomy in Heidelberg, Germany, where she is a member of the Adaptive Optics Lab and the Planet and Star Formation Group